Funds from this grant support the work of Brent Stephens at the Illinois Institute of Technology to develop and document an open network of inexpensive, standardized, and synchronized measurement devices for recording long-term indoor environmental and building operational parameters. Stephens will focus on the parameters that are most likely to influence indoor microbial communities, including environmental conditions (air temperature, relative humidity, light), characteristics of the building’s heating, ventilation, and air conditioning systems (air flow rates, air exchange rates), human occupancy, and surface environmental conditions (surface temperature and water activity).In addition to developing and testing the sensors themselves, Stephens will make public the documentation and directions for how to build and deploy the sensors. He will also prepare several peer-reviewed publications for the microbial ecology, building science, and sensor development communities.